Technical Field
The present invention relates to semiconductor processing, and more particularly to an ion flow barrier and methods for fabrication to reduce electromigration of ions while maintaining low resistance interconnect interfaces.
Description of the Related Art
Reliability and electromigration performance are negatively impacted as barrier thickness is downscaled in back end of the line (BEOL) Cu interconnects. In addition to risks associated with barrier continuity on sidewalls, discontinuities in the barrier (such as TaN) at a via bottom lead to breakdown of “short-length” criterion. This criterion requires blocking of Cu ion flow at a via bottom to prevent massive Cu ion migration from level to level.